1. Field of the Invention
This invention relates to loading dock equipment and in particular to a dock structure having bumpers that are vertically adjustable to accommodate vehicles of different sizes.
2. Prior Art
Most loading docks are designed for standard truck trailers which typically have a bed height of 48 to 52 inches. Many new "high-cube" trailers have a bed height of 32 to 36 inches. The difficulty is that dock bumpers placed high enough for a standard trailer will impede access to low trailers. Conversely, bumpers placed for the low trailers will allow standard trailers to pass over and impact the building. There are several conventional solutions to accommodate both low and standard height trailers but all involve compromises that impede effective dock operations.
The simple solution is to have separate docks, each having the proper height for the trailer, but this increases cost of a dock installation and reduces the flexibility of a single dock to handle various trailers. As a consequence the dock may be unoccupied for periods of time because the trailers do not match the configuration.
Another solution is to use wheel riser ramps or hydraulic truck levelers mounted on the driveway. However, this solution interferes with the ability of vehicle restraints to engage the ICC bar of the low trailer when it is raised to dock height, and also interferes with snow removal in northern climates. Some low trailer applications can be serviced by using long dock levelers with extended below dock range. However, most dock levelers are limited to 7 feet width as a wider leveler would not allow sufficient space at each side to mount the bumpers to engage the trailer and if the cargo to be loaded is the full width of the trailer, it will not pass between the sides of the leveler pit when the leveler is below the dock floor. It is also expensive to install.